Many routers implement a separation of control and forwarding functions. Certain processors of these routers are dedicated to control and management task (and perform functions in so called “control plane” of these routers), while other processors of these routers are dedicated to data forwarding tasks (and perform functions in so called “data plane”). This separation creates the possibility of maintaining a router's data plane functionality of data forwarding when the control plane is restarted (e.g., during a control software upgrade), thus restarting the control plane does not impact data forwarding of the data plane. Such mechanism is generally called “graceful restart” or “non-stop forwarding.” In a network supporting open shortest path first (OSPF) protocol, an OSPF enabled router can stay on the data forwarding path thus keeps an active data plane while its routing software is restarted through a graceful restart process.
During a graceful restart process of an OSPF network, when the network topology remains stable, the restarting router is kept on the forwarding tables of its neighboring routers. When a restarting OSPF enabled router restarts its routing software, its database may be empty or significantly different from its neighboring routers, thus the data synchronization of the restarting OSPF enabled router with its neighboring routers may take significant time. In a scaled environment, where the restarting OSPF router needs to synchronize its database with many neighboring routers, the data synchronization process can be lengthy and resource consuming.